Case of the Month #9: Persistent Left Arm Pain by Dr Richard Wassall

Published: 02/11/2021

Discussion: Treatment

As with any complex chronic pain case, initial management should include patient education, physiotherapy, symptomatic pain management and psychological assessment through a structured Multidisciplinary Team (MDT) approach. Unfortunately in this case, our patient was in extremis, and needed help before a full MDT could convene. Her initial assessment was also complicated by language barriers, and the importance of a professional independent interpreter being present at every consultation and treatment session should not be underestimated.

Given the high opioid requirements of the patient, an urgent non-opioid intervention was needed at first to manage the symptoms and help build rapport. Sympathetic blocks are generally not recommended for management of CRPS, but this is mostly due to the paucity of high quality high fidelity clinical trials in the area rather than lack of effect in individual cases, and these are often offered in practice. Low dose Ketamine and Lidocaine infusions have been used to manage flares of symptoms, but doses and lengths of treatment cycles remain unclear. In this case, a single infusion of Lidocaine (2 mg/kg ideal body weight) with intensive physiotherapy was enough to gain control of the symptoms in the first instance, and allowed a discussion of the management of the patient’s dependence on opioids as her main analgesia. Many patients with CRPS are referred having been treated with opioids first line as a method of pain control, particularly in the acute phases of the condition, and it becomes the job of the pain service or drug dependence services to rationalize and taper opioids to minimize side effects whilst maintaining function. Tapentadol was useful here as an opioid rotation device in order to aid her opioid decrease once her Amitriptyline had been weaned down. Tapentadol has both opioid activity (mu agonist) and selective noradrenergic reuptake inhibitor activity, and as a result, can often be helpful when other opioids are having lower effect than would be expected for the prescribed dose due to patient tolerance.

In order to help manage the dystonia, Baclofen, a GABAB receptor agonist, can be useful. Oral Magnesium may also have helped with muscle relaxation and analgesia, but the studies are lacking. Most studies only show a minor benefit of Vitamin C in preventing CRPS post-surgery, but the patient was started on Vitamin C, as it is a low cost and low risk intervention, and she felt that she wanted to take it, based on the idea that it  was something that she could control and potentially contribute to her recovery. The data on Vitamin C in prevention of CRPS is mixed, especially due to the quality of evidence, but there are many physicians who advocate the use of Vitamin C 500 - 1500 mg post ankle or distal radial surgery to prevent CRPS. Other medications that can be useful in CRPS include NSAIDs, Bisphosphonates and Steroids, especially in the early proinflammatory stages, and vasodilators (calcium channel blockers, alpha-sympathetic blockers or phosphodiesterase-5 inhibitors), especially in the later “cold” CRPS to prevent microvascular ischaemia-reperfusion injury. Antiepileptics and other antidepressants have also been tried.

Non-pharmacological invasive interventions include spinal cord stimulators (SCS) and dorsal root ganglion stimulation (DRGS), both of which should be considered where CRPS is refractory to rehabilitative and pharmacological therapies. In SCS, electrodes are placed percutaneously into the epidural space and attached to a pulse generator. Electrical stimulation of the dorsal column is thought to mask pain sensation, and the perception of pain is reduced. DRGS employs a similar mechanism, but instead of stimulating the dorsal column, it stimulates the dorsal root ganglion to achieve pain relief. Emerging evidence is that DRGS may be superior to SCS in treating CRPS and other types of chronic pain, but further work is needed.

CRPS treatment should involve a multidisciplinary team approach to help patients overcome the high emotional toll associated with their suffering, and also to help them conquer the inevitable fear of movement that they develop surrounding the affected portion(s) of their body. Psychologists and physiotherapists are integral members of the process who can make big enhancements to the recovery rates in CRPS, and their input is considered by some to be the first line intervention in CRPS. Two therapies which have gained significant popularity and appear to give improvement in pain and mobility are: graded motor imagery, where patients identify limb laterality with imagination, images, and mirrors; and mirror therapy, where patients describe both the affected and unaffected limb, imagine the movements bilaterally, and finally look at the mirrored limb with and without movement. Other therapies including hypnosis, relaxation therapy, thermal biofeedback, and other coping and management techniques all show improved outcomes in small trials, but large scale research trials are needed. In practice, the role of psychotherapy, occupational therapy and physiotherapy is to improve motivation, movement, functionality and quality of life, helping patients to cope better with their condition. In this respect, starting these therapies early in the course of the clinical progression is paramount to allow patients to make the changes necessary to ultimately self-manage.

CRPS remains an under-investigated condition complicated by multifactorial aetiologies and variants that necessitate an individualized patient-centred management plan. Further research is needed to help solidify our current management options, whilst innovative new investigations and therapies will continue to progress our understanding and treatment of this debilitating syndrome.